What is the filter in the camera for?

There are many kinds of filters, each with its own purpose. Commonly used filters include UV mirror, gradient mirror, ND mirror, medium gray mirror and panchromatic mirror. Various filters are also divided into different colors and sizes. This will be more complicated and contain a lot of content. I suggest you go to some professional websites to check some information, and you will know at a glance. Mai Sha photographic equipment website has knowledge about filters, as well as pictures of various filters. I recommend you to learn.